Persistent, Extensive Channelized Drainage Modeled Beneath Thwaites Glacier, West Antarctica
Persistent, Extensive Channelized Drainage Modeled Beneath Thwaites Glacier, West Antarctica
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西南极洲思韦茨冰川下持续、广泛的渠道排水模型
DOI：
10.5194/tc-2021-338
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
D. Schroeder
中科院分区：
文献类型：
--
作者：
A. Hager;M. Hoffman;S. Price;D. Schroeder
抽象的。冰下水文学是对冰川和冰盖的基底摩擦和动力学的主要控制。在低流量下，冰下水流过高压，片状系统，导致低有效压力。然而，在高流量下，冰下水将上覆冰融化成局部通道，有效地将水从床中移除，从而增加有效压力和基底摩擦。最近的观测表明，沟道化冰下流存在于思韦茨冰川下方，但目前还不清楚稳定的沟道化在南极洲西部是否可行，那里不存在表面融化，河床上的水有限。在这里，我们使用MPAS-Albany陆冰模型运行一套超过130个冰下水文模拟的Thwaites冰川在广泛的物理参数选择，以评估渠道化的可能性。然后，我们缩小了我们的范围内可行的模拟比较建模水的厚度，以前观察到的雷达镜面反射的内容，这表明平坦，空间广泛的水体在床上。在我们所有数据兼容的模拟中，稳定的通道可靠地形成在接地线的100-200 km范围内，并在冰-海洋边界处达到35-110 m3 s−1的单个放电速率。虽然在我们的模拟中，在200公里宽的冰川上通常只形成一到两个通道，但它们的高效率将水排出冰川的整个横向范围。当禁用通道化时，没有类似于观察到的镜面反射内容的模拟。我们的研究结果表明，渠化冰下水文有两个后果的Thwaites冰川动力学：（i）放大海底融化的终端和冰架，而（ii）同时提高有效压力在100公里的接地线，增加基底摩擦。从我们的建模隐含的有效压力的分布不同于通常用于大规模冰盖模型的参数化，这表明更多的过程为基础的参数化的发展可能是必要的。
Abstract. Subglacial hydrology is a leading control on basal friction and the dynamics of glaciers and ice sheets. At low discharge, subglacial water flows through high-pressure, sheet-like systems that lead to low effective pressures. However, at high discharge, subglacial water melts the overlying ice into localized channels that efficiently remove water from the bed, thereby increasing effective pressure and basal friction. Recent observations suggest channelized subglacial flow exists beneath Thwaites Glacier, yet it remains unclear if stable channelization is feasible in West Antarctica, where surface melting is nonexistent and water at the bed is limited. Here, we use the MPAS-Albany Land Ice model to run a suite of over 130 subglacial hydrology simulations of Thwaites Glacier across a wide range of physical parameter choices to assess the likelihood of channelization. We then narrow our range of viable simulations by comparing modeled water thicknesses to previously observed radar specularity content, which indicates flat, spatially extensive water bodies at the bed. In all of our data-compatible simulations, stable channels reliably form within 100–200 km of the grounding line, and reach individual discharge rates of 35–110 m3 s−1 at the ice-ocean boundary. While only one to two channels typically form across the 200 km width of the glacier in our simulations, their high efficiency drains water across the entire lateral extent of the glacier. No simulations resembled observed specularity content when channelization is disabled. Our results suggest channelized subglacial hydrology has two consequences for Thwaites Glacier dynamics: (i) amplifying submarine melting of the terminus and ice shelf, while (ii) simultaneously raising effective pressure within 100 km of the grounding line and increasing basal friction. The distribution of effective pressure implied from our modeling differs from parameterizations typically used in large-scale ice sheet models, suggesting the development of more process-based parameterizations may be necessary.
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影响因子：
18.3
作者：
Adusumilli S;Fricker HA;Medley B;Padman L;Siegfried MR
通讯作者：
Siegfried MR
简短通讯：思韦茨冰川空腔演化
DOI：
10.5194/tc-2021-66
发表时间：
2021
期刊：
--
影响因子：
--
作者：
Bevan S
通讯作者：
Bevan S
冰川峡湾陆架交换的几何约束
影响因子：
3.5
作者：
Zhao, Ken X.;Stewart, Andrew L.;McWilliams, James C.
通讯作者：
McWilliams, James C.
影响因子：
18.3
作者：
Chandler, D. M.;Wadham, J. L.;Hubbard, A.
通讯作者：
Hubbard, A.
西南极洲思韦茨冰川下方的床型变异性和耕作（不）连续性
影响因子：
2.9
作者：
Muto, Atsuhiro;Alley, Richard B.;Parizek, Byron R.;Anandakrishnan, Sridhar
通讯作者：
Anandakrishnan, Sridhar